FIXED MDB9979SKZ0 Maytag Dishwasher unresponsive

[blinkingled]

Model Number

MDB9979SKZ0

Brand

Maytag

Age

1-5 years

2 year old Maytag MDB9979SKZ0 dishwasher has been unresponsive (no lights on control panel, no drain motor activation on startup);
Tech sheet W11366142A (see attachment which is Rev C instead of A but wiring diagram appears identical)

Tried the following:
1. Disconnected the control panel from control board; reset breaker (dedicated circuit); Board/ACU initialized (fast blinking) followed by slow blinking (which is considered normal ACU operation per tech sheet); NO sound from drain motor
2. Ordered and replaced a new control board W11410063 and repeated step 1 (same response, no activation of drain motor)
3. Verified door switch for connectivity by meter
4. Inspected old control board connections; no burnt traces on PCB.
5. Tried searching for thermal fuse on parts websites ; They recommend a new wiring harness W11397505
6. Inspected existing wiring harness; the black load wire to the board has an inline fuse which looks dark brown/discolored (see image); However, non contact voltage tests normal on the black load wire on either side of the fuse; despite brown discoloration on the end of the fuse, the wire element looks unbroken by my assessment
The dishwasher has been used sparingly and otherwise worked great. The only service done was a Maytag recommended replacement of the heater element (complimentary) appx 2 months ago. Any ideas welcome. Thank you for your time and input.

 

[Jake]

Here's the service manual: https://drive.google.com/file/d/16JlVUq65LUiZdSpsIJJqAnEAS7sDAYHL/view?usp=share_link Look on page 27 where it says:
Won't run or power up (“Dead” keypad/console) --->No operation--->No keypad response--->No LEDs or display

Here's the control panel for your model: Panel-Cntl W11413965

6. Inspected existing wiring harness; the black load wire to the board has an inline fuse which looks dark brown/discolored (see image); However, non contact voltage tests normal on the black load wire on either side of the fuse; despite brown discoloration on the end of the fuse

You ohm tested that fuse and it has continuity?

 

[blinkingled]

The fuse is part of the black wire. I have to cut it to check continuity. Cannot see this described in any part website. Since the board lights up with a slow blink and I can hear a couple of relays when I turn it on, I assumed that the black wire is supplying power. Haven't tested the actual voltage yet.

 

[Jake]

Ok, this is a very strange situation, all I can say it to go by what the service manual I posted the link to above, says to check for this problem.

You can also test that fuse from the control board, look on Page 3-3 in the service manual, remember to disconnect power first before ohm testing.

 

[blinkingled]

1. Despite the brown discoloration the board was getting 120VAC; BTW, this unique harness (with the inline fuse attached to the black L1 wire) is not in stock and not available even at Whirlpool
2. When I checked the board for 5V and 13V DC supplies; the 13V DC supply test read OL on my DC voltmeter; While disconnecting and reconnecting the orange P11 connector with the ACU board powered, suddenly the drain motor came to life! This was proof that the ACU control board was NOT the problem.
3. Interestingly, when I attached the control panel to the ACU there was no light and no drain motor; However, removing and reattaching the P11 Orange connector seems to *reset* the ACU to run the drain pump to confirm normal ACU function again. This missing piece of information would have saved me from ordering an expensive no return ACU control board had I known it.
4. I quickly jumped to check the UI control panel and lo and behold there was evidence of water intrusion and corrosion over the circuit board involving one of the microswitches; Cleaning it was not good enough and I have ordered the same part as

 

[blinkingled]

FIXED!!The new UI ordered from AppliancePartsPros arrived within 2 days and the problem is solved!! I wrapped the replacement UI in shrink wrap before attaching to the door panel. 2 important points for others who find themselves in a fix.
1. The troubleshooting steps for resetting the control board power to check if the board(ACU) or the panel (UI) is at fault is missing a very important step; if there is no evidence of drain pump activity after disconnecting the UI cable from board, *but the board is flashing a slow blinking LED (indicating normal ACU function)*, one should disconnect the orange interface cable and reconnect to clear the memory from the ACU board; this will activate the drain motor if the board is ok. If this step (disconnect/reconnect Orange cable) does not start the drain motor then only you should order a new replacement control board.
2. The most likely reason for the failure of the user interface on the *TOP CONTROL* models is the easy intrusion of water/liquids from wet hands pressing the START button; So, dont touch the control panel with wet hands (like when you are manually rinsing dishes!!); Better yet, avoid buying the TOP CONTROL model in favor of the front control model if you are shopping for one.

Thank you Admin Jake!! The user video from Irickley was also helpful.

P.s: I now have a new OEM replacement control board W11410063 ; Would you recommend I sell it or hold on to it for the future just in case?

 

[Jake]

Excellent, Glad to hear the new control panel(UI) fixed it.

Thanks for the update and added information you posted!

P.s: I now have a new OEM replacement control board W11410063 ; Would you recommend I sell it or hold on to it for the future just in case?

Its up to you, either way is fine.